The present invention relates to a metal laminate gasket with an auxiliary sealing bead extending toward an engine part to seal around a hole.
A metal laminate gasket for sealing between engine parts has been used widely, wherein a plurality of metal plates is laminated together. In one type of the metal laminate gaskets, such as Japanese Utility Model Publication (KOKOKU) No. 54-25532, one of outer plates is turned around the hole to be sealed and covers outside the hole so that fluid passing through the hole does not enter between the plates.
A cylinder head gasket G as shown in FIGS. 1 and 2 is this kind of gasket, which includes a plurality of cylinder bores Hc, water holes Hw, oil holes Ho and bolt holes Hb. The gasket G is formed of outer plates 10, 14, three middle plates 11, 12, 13 and a wire ring 15. The plate 10 includes a curved portion 10a and a flange 10b, and the plate 11 includes a bead 11a.
The outer plate 14 defines an underside of the gasket G, but an inner portion 14a of the outer plate 14 is located inside the flange 10b to prevent fluid or gas from entering between the plates of the gasket. The plate 13 with a large opening is situated above a main part of the plate 14 to adjust height of the gasket at the flange 10b and the main part of the plate 14. There is a lateral space 16 between the plate 13 and the flange, through which the plate 14 extends.
In this gasket G, a bead 14b is formed under the plate 13 to project outwardly or toward an engine part so that the bead 14b abuts against the engine part to prevent leakage of fluid through small dents or grooves on the engine part. This bead 14b is useful for sealing in case the engine part is made of hard material, such as iron.
However, since side portions of the bead 14b are located under the same plate, i.e. plate 13, and especially, one side of the bead 14b is located close to an inner edge of the plate 13, when the gasket G is compressed, the bead 14b causes undesirable force.
Namely, when the bead 14b is compressed, since the side of the bead close to the inner edge of the plate 13 is not firmly supported, the side of the bead is forced to move toward the cylinder bore Hc to thereby raise the flange 10b outwardly. Also, when the bead 11a is compressed, the same side of the bead 14b is pulled toward the cylinder bore, so that the bead 14b does not operate as intended. Further, the plate 14 may be partly twisted due to uneven force caused by the bead 14b.
The bead 14b abutting against the engine part is useful for sealing against the engine part. However, such bead 14b of the conventional gasket may cause undesirable force to cause leakage of the fluid.
Accordingly, one object of the invention is to provide a metal laminate gasket with an auxiliary sealing bead, which can seal properly around a hole without causing undesirable force against other parts of the gasket.
Another object of the invention is to provide a metal laminate gasket with an auxiliary sealing bead as stated above, wherein the auxiliary sealing bead can absorb movement of a part of a plate to eliminate distortion of the gasket.
A further object of the invention is to provide a metal laminate gasket as stated above, which can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.